Communication plug with improved crosstalk

ABSTRACT

A communication plug having a plug body and a plurality of contact pairs at least partially within the plug body, the contact pairs including an inherent asymmetric coupling between individual contacts of one of the contact pairs and other individual contacts of another of the contact pairs. Second asymmetric coupling elements are connected between the individual contacts of one of the contact pairs and the other individual contacts of another of the contact pairs. The second asymmetric coupling elements, when combined with the inherent asymmetric coupling, provide a balanced symmetric coupling between the individual contacts of one of the contact pairs and the other individual contacts of another of the contact pairs.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/202,166, filed Mar. 10, 2014, which is a continuation of U.S.application Ser. No. 12/909,030, filed Oct. 21, 2010, which issued asU.S. Pat. No. 8,690,598 on Apr. 8, 2014, the entirety of which arehereby incorporated by reference.

FIELD OF THE INVENTION

The present disclosure relates generally to communication plugs withimproved crosstalk, and more particularly, to communication plugs withbalanced crosstalk.

BACKGROUND OF THE INVENTION

The current ANSI/TIA-568-C.2 structured cabling standard defines therequirements for component and channel operation from Category 5e(CAT5E) to Category 6A (CAT6A), including requirements for RJ45 typeplugs such as are commonly used in communication networks. Such plugstypically are connected to respective four-twisted-pair communicationcables, and can mate with RJ45 jacks in a variety of network equipmentsuch as patch panels, wall jacks, Ethernet switches, routers, servers,physical layer management systems, power-over-Ethernet equipment,security devices (including cameras and sensors), and door accessequipment. RJ45 plugs can also mate with RJ45 jacks in workstationperipherals, such as telephones, fax machines, computers, printers,copiers, and other equipment. Plugs are components in correspondingchannels, which channels can connect a user's computer to a router, forexample, providing connection to the Internet, or other local areanetwork (LAN) devices.

A typical structured cabling environment can include a commercialbuilding having offices/work areas with computer workstations which areconnected to a LAN, and to the Internet via patch panels, wall jacks,Ethernet switches, routers, servers, and/or physical layer managementsystems. A variety of cabling/cords such as patch cords, zone cords,backbone cabling, and horizontal cabling are used throughout thebuilding to interconnect the aforementioned equipment. Cabinets, racks,cable management, overhead routing systems, and other such equipment canbe used to organize the equipment and cabling into a manageable system.

As the complexity, data rate and frequency of operation increase forsuch communication networks, so increases the potential for undesirableinteractions between the different channel components such as plugs,jacks and cable. As with any communication system, these communicationnetworks have minimum signal-to-noise requirements to reliably transmitand receive information sent through the channel. A channel in suchsystems includes the four-twisted-pair (four transmission lines)transmission medium operating in full duplex communication mode. For 10gigabit Ethernet (CAT6A), for example, each twisted pair (circuit) isoperating at 2.5 gigabit/s to give the corresponding channel the full 10gigabit capacity. One form of noise in such channels is crosstalk, whichis a disturbance in a circuit (or a cable pair) signal, caused by asignal in an adjacent circuit (cable pair).

Crosstalk can be characterized as occurring at the near-end (NEXT) andthe far-end (FEXT) of a transmission line between differentialconductive path pairs within a channel (referred to as internal NEXT andinternal FEXT) or can couple to differential conductive path pairs in aneighboring channel (referred to as alien NEXT and alien FEXT). Becauseof the differential signals which are typically used in suchcommunication systems, so long as the same noise signal (common modenoise) is added to each conductive path in the conductive path pair,then the voltage difference between the conductive paths remains thesame and such common mode crosstalk has no effect on the differentialsignal, for a given twisted pair.

As data transmission rates have steadily increased, crosstalk due tocapacitive and inductive couplings, due at least in part to thedistributed electrical parameters of the various circuit components,among the closely spaced parallel conductors within the plug and/or jackhas become increasingly problematic. If the capacitive and inductivecouplings between the four pairs of a channel are not equal, animbalance exists, and the consequence of such imbalance is phenomenoncalled mode conversion. In mode conversion, common mode noise isconverted to a differential signal, and the differential signal can beconverted to a common mode signal. What may have been a relativelyharmless common mode signal from a nearby channel, in the presence ofcircuit imbalance in the victim channel, is converted to differentialsignal in the victim channel thereby detrimentally reducing the signalto noise ratio of the victim channel. FIGS. 1A and 1B show a typicalcommunication plug, with the plug body shown translucent to illustrateinternal wires and contacts. FIG. 1A is an upper right-hand perspectiveview and FIG. 1B is an upper plan view. The plug 100 includes an RJ45plug body 102 and a strain relief boot 114. Four differential wire pairs108 (108 a, 108 b, 108 c, and 108 d) are disposed within the plug body.

During a typical installation, the pairs 108 are untwisted, aligned intothe plug body 102, and crimped with a handheld tool so that the pairs108 make contact with the insulation piercing contacts (IPCs) 109 at thenose of the plug. The IPCs provide the connection point when the plug100 is inserted into an RJ45 jack. Although this design is per theANSI/TIA-568-C.2 structured cabling standard, this design results inunbalanced capacitive and inductive coupling between neighboringconductors in the IPC area and along the untwisted parallel portion ofthe wires within the plug body 102. For interoperability and backwardscompatibility, ANSI/TIA-568-C.2 requires that the plug have internalcrosstalk within a de-embedded range, and that contacts 1 through 8 arearranged in order with contact 1 adjacent to contact 2, which isadjacent to contact 3, etc. This orientation of contacts results in aninherently unequal amount of coupling between the conductors of eachpair. Capacitive and inductive coupling between neighboring circuits ishighly dependent on proximity, i.e., the closer a victim circuit is toan aggressor circuit the higher the coupling, and consequently, thegreater the coupled signal in the victim circuit. The capacitive andinductive coupling between conductor 3 of pair 3-6 and conductor 2 ofpair 1-2 is much stronger than the capacitive and inductive couplingbetween conductor 3 of pair 3-6 and conductor 1 of pair 1-2 due to thecloser proximity between conductor 2 of pair 1-2 and conductor 3 of pair3-6. This poor balance leads to mode conversion, which causes a portionof a differential signal propagating through the plug on pair 1-2 to beconverted to a common mode signal on pair 1-2. Due to the reciprocalnature of mode conversion, a portion of any common mode signalpropagating though the plug on pair 1-2 will be converted to adifferential signal on pair 1-2. The negative impact from poor balanceand the associated mode conversion in the RJ45 plug 100 can be seen inmany of the measurements made on a Category 6A channel, such as aliencrosstalk parameters (e.g. power sum alien near-end crosstalk (PSANEXT)and power sum alien attenuation to crosstalk ratio, far-end (PSAACRF))and balance parameters (e.g. transverse conversion loss (TCL) andtransverse conversion transfer loss (TCTL)). The manufacturinginconsistencies of the manual untwisting process mentioned above canalso lead to performance variability.

Poor balance in the plug 100 and the corresponding mode conversion mayalso lead to degraded electromagnetic interference/electromagneticcompatibility (EMI/EMC) performance for a Category 6A channel. Thecommon mode signal that is created from a differential signal passingthrough an unbalanced plug 100 will radiate into the surroundingenvironment. Higher mode conversion corresponds to greater radiatedenergy. Conversely, when a channel is subjected to electromagneticinterference from outside sources such as walkie talkies, cellphones,etc., a common mode signal is induced in the channel. When that commonmode signal passes through an unbalanced plug 100, a portion of thatsignal is converted to a differential signal, which will contribute tothe total noise in the channel. Higher mode conversion results inproportionally higher differential noise.

Another shortcoming of the typical RJ45 plug 100 relates to the“super-pair” phenomenon. Industry standards require the plug contacts tohave contacts 3 and 6 split around contacts 4 and 5. In the plug 100,wire pair 3-6 (reference numeral 108 b) is also split around wire pair4-5 (reference numeral 108 c). This splitting of wire pair 3-6 resultsin conductor 3 coupling more strongly than conductor 6 to pair 1-2(reference numeral 108 a) and conductor 6 coupling more strongly thanconductor 3 to pair 7-8 (reference numeral 108 d). Because the signal onconductor 3 is at the opposite polarity of the signal on conductor 6,pair 1-2 will be at the opposite polarity of pair 7-8. Depending on thedesign of the connecting hardware and cabling, pair 1-2 and pair 7-8 mayact as a differential “super-pair” and propagate the crosstalk from pair3-6 through the channel. The “super-pair” signal can degrade the PSANEXTand PSAACRF performance of a Category 6A channel.

What is needed in the art is a communication plug which has balancedcoupling between pairs resulting in balanced crosstalk between the fourpairs, which can provide improved PSANEXT, PSAACRF, TCL, and/or TCTLperformance as well as enhanced EMI/EMC performance caused by loweredelectromagnetic radiation and higher tolerance of electromagnetic fieldlevels from interfering sources.

SUMMARY OF THE INVENTION

The invention comprises, in one form thereof, a communication plug thatmakes electrical contact between a communication cable and acommunication jack. The plug includes a plug body, a circuit board,contacts for the cable, and contacts for a jack. The plug body has acavity for receiving the communication cable, where the communicationcable enters the plug body along an axis. The circuit board is locatedin the cavity and has a plurality of traces arranged to provide couplingbetween at least two of the plurality of traces. The circuit board hasat least one surface that is angled relative to the axis.

The angled surface of the circuit board may be implemented by installingthe circuit board at an angle in the cavity of the plug body, forexample. Alternatively, the circuit board may be placed on a molded bodyhaving an angled surface relative to the axis. For example, the circuitboard may be a flexible printed circuit board wrapped around the moldedbody.

Common mode chokes may be included on the circuit board for each wirepair. This can help to attenuate common mode signals that may bepropagating on the wire pairs, without significantly attenuatingdifferential signals.

The invention comprises, in another form thereof, a communication plugfor making electrical contact between a communication cable with aplurality of cable conductor pairs and a communication jack, whichincludes a plug body having a cavity for receiving the communicationcable, and a plurality of contact pairs at least partially within theplug body. The plurality of contact pairs make electrical contact withcorresponding cable conductor pairs, wherein at least one contact of thecontact pairs is approximately equidistant to both contacts of anotherof the contact pairs.

The invention comprises, in another form thereof, a communication plughaving a plug body and a plurality of contact pairs at least partiallywithin the plug body, the contact pairs including an inherent asymmetriccoupling between individual contacts of one of the contact pairs andother individual contacts of another of the contact pairs. Secondasymmetric coupling elements are connected between the individualcontacts of one of the contact pairs and the other individual contactsof another of the contact pairs. The second asymmetric couplingelements, when combined with the inherent asymmetric coupling, provide abalanced symmetric coupling between the individual contacts of one ofthe contact pairs and the other individual contacts of another of thecontact pairs.

The invention comprises, in another form thereof, a communication systemincluding a communication cable and/or communication equipment. Acommunication plug is connected to the communication cable and/or thecommunication equipment. The communication plug includes a plug body anda plurality of contact pairs at least partially within the plug body,the contact pairs having an inherent asymmetric coupling betweenindividual contacts of one of the contact pairs and other individualcontacts of another of the contact pairs. Second asymmetric couplingelements are connected between the individual contacts of one of thecontact pairs and the other individual contacts of another of thecontact pairs. The second asymmetric coupling elements, when combinedwith the inherent asymmetric coupling, provide a balanced symmetriccoupling between the individual contacts of one of the contact pairs andthe other individual contacts of another of the contact pairs.

The invention comprises, in another form thereof, a communication plugwith a plug body having a cavity, a circuit board located in the cavityand having a plurality of traces defining a plurality of conductorpairs, and a common mode choke connected between two of the tracesdefining one of the pairs.

The invention comprises, in another form thereof, a method of designinga communication plug, including the steps of: reducing inherentasymmetric crosstalk in the plug; and adding another asymmetriccrosstalk in the plug to produce symmetric crosstalk in the plug.

The invention comprises, in another form thereof, a communication plugfor making electrical contact between a communication cable and acommunication jack, including a plug body having a cavity for receivingthe communication cable, wherein the communication cable enters the plugbody along an axis. A circuit board is located in the cavity and has aplurality of traces. Contacts are included for making electrical contactbetween traces on the circuit board and the jack, wherein the contactseach have a surface area parallel to the axis, the surface area beingsmaller than a predetermined value.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages, and the manner ofattaining them, will become more apparent and the disclosure will bebetter understood by reference to the following description taken inconjunction with the accompanying drawings, wherein:

FIG. 1A is a perspective view of a typical communication plug, with theplug body shown translucent to illustrate internal wires and contacts;

FIG. 1B is another perspective view of the typical communication plug ofFIG. 1A, with the plug body shown translucent to illustrate internalwires and contacts;

FIG. 2A is a perspective view of an embodiment of a communication plugaccording to the present invention, with the plug body shown translucentto illustrate internal components;

FIG. 2B is another perspective view of the communication plug of FIG.2A, with the plug body shown translucent to illustrate internalcomponents;

FIG. 3A is a side view of an assembly of wires engaged with a circuitboard, in accordance with the configuration of FIGS. 2A and 2B;

FIG. 3B is a perspective view of the assembly of FIG. 3A;

FIG. 4A is a schematic view of a semi-balanced IDC layout of oneembodiment of a circuit board according to the present invention;

FIG. 4B is a schematic view of a balanced IDC layout of one embodimentof a circuit board according to the present invention;

FIG. 5 is a side view of the communication plug of FIGS. 2A and 2B, withthe plug body shown translucent to illustrate internal components;

FIG. 6 is an exploded perspective view of an embodiment of a circuitboard of the plug of FIGS. 2A and 2B, showing how the plug contacts areinserted, according to one embodiment of the present invention;

FIG. 7 is a perspective view of a first contact type and a secondcontact type used as shown in FIG. 6, according to one embodiment of thepresent invention;

FIG. 8A is a perspective view of another communication plug, with theplug body shown translucent to illustrate internal components, accordingto one embodiment of the present invention;

FIG. 8B is a perspective view of another side of the communication plugof FIG. 8A, with the plug body shown translucent to illustrate internalcomponents;

FIG. 9A is a perspective view of an assembly comprising a circuit board,body, and IDCs for use in the communication plug of FIGS. 8A and 8B;

FIG. 9B is a close-up perspective cutaway view of the assembly of FIG.9A, illustrating construction details;

FIG. 10A is a fragmentary side view of an assembly comprising a circuitboard, body, IDC's, wires, and wire guide interfacing with a jackcontact assembly;

FIG. 10B is an additional side view showing the assembly of FIG. 10Ainside a plug body;

FIG. 11A is a perspective view of the assembly of FIG. 9A, showing theIDC's installed;

FIG. 11B is a perspective view of an assembly similar to the one shownin FIG. 11A, showing the IDC's installed in an alternativeconfiguration;

FIG. 12 is a perspective view of the underside of an assembly similar tothe one shown in FIG. 11B, illustrating contact pads;

FIG. 13 is a perspective view of a communication plug with common modechokes, with the plug body shown translucent to illustrate internalcomponents;

FIG. 14 is a perspective view of an assembly of wires engaged with acircuit board of FIG. 13;

FIG. 15A is a cross-sectional side view of a portion of a plug havingchokes;

FIG. 15B is a perspective view of a portion of a plug having chokes;

FIG. 16 is a PCB layout of two layers of the PCB used in the plug ofFIGS. 2A and 2B;

FIG. 17 is a PCB layout of the other two layers of the PCB used in theplug of FIGS. 2A and 2B; and

FIG. 18 is a PCB layout of all four layers from FIGS. 16 and 17.

Corresponding reference characters indicate corresponding partsthroughout the several views. The exemplifications set out hereinillustrate one preferred embodiment of the invention, in one form, andsuch exemplifications are not to be construed as limiting the scope ofthe invention in any manner.

DETAILED DESCRIPTION

Referring to the drawings, FIGS. 2A-7 relate to a first embodiment,while FIGS. 8A-15B related to a second embodiment. The illustratedembodiments are described using examples, and are not intended to limitthe scope of the claimed invention in any way. For example, one or morecombinations, or subcombinations, of the two illustrated embodimentsmight fall within the claimed invention and are intended to be includedwithin the scope of protection. The claims appended hereto set forth theintended scope of the invention.

FIGS. 2A and 2B are isometric views of a communication plug 200, withthe plug body 202 shown translucent to illustrate internal components.The plug 200 is connected through a strain relief boot 214 to a cable204 comprising an outer insulating jacket 206 surrounding wire pairs 208that terminate through a wire guide 210 in the plug body 202 at acircuit board 212. The wire pairs 208, wire guide 210, and circuit board212 are illustrated in further detail in FIGS. 3A-7.

One function of the circuit board 212 is to provide a means ofintroducing coupling in the data path in order to provide an appropriateamount of crosstalk, as required by the TIA-568-B.2-10 standard. Thecircuit board 212 is preferably a printed circuit board (PCB) thatincludes embedded capacitors and/or inductors arranged in such a way toachieve a desired balance and crosstalk performance. The exact valuesand arrangement of these capacitors and/or inductors will depend on theelectrical characteristics of the particular plug 200 and its intendedapplication.

FIGS. 3A and 3B show an assembly 300 of wires engaged with a circuitboard, in accordance with the configuration of FIGS. 2A and 2B. FIG. 3Ais an elevation view, while FIG. 3B is an isometric view. The assembly300 illustrates how the plug 200 would look if the plug body 202 andstrain relief boot 214 were to be removed.

The assembly 300 includes the outer insulating jacket 206, wire pairs208, and circuit board 212. The circuit board 212 includes contacts 304,for making electrical contact with plug interface contacts (PICs) in acorresponding jack (not shown). The circuit board 212 also includesinsulation displacement contacts (IDCs) 302 a-b for making electricalconnections between traces (not shown) on the circuit board 212 and thedifferential wire pairs 208. The IDCs 302 a-b are preferably press-fitinto the circuit board 212 on both the top (302 a) and bottom (302 b)sides.

FIGS. 4A and 4B are plan views of two alternative conceptualconfigurations (412 a-b) for the IDCs of circuit board 212. Bothconfigurations place the IDCs in a staggered orientation, withsubstantially equal distances between neighboring contacts to achievebalanced coupling between neighboring pairs. In the first embodiment(FIG. 4A), the IDC press-fit holes 416 a in the circuit board 412 a areconfigured in a diagonal orientation with respect to the length of thecircuit board 416 a. As such, the IDC press-fit hole for a particularwire pair that is nearest any other hole for a different wire pair isarranged to be equi-distant to both holes for that different wire pair,so that more balanced coupling is provided between adjacent IDC pairs.Therefore, in the circuit board 412 a, distance D1 is equal to distanceD2, distance D3 is equal to distance D4, and distance D5 is equal todistance D6. Similarly, in the second embodiment (FIG. 4B), in order toprovide the same type of balanced coupling, the press-fit holes 416 bare arranged diagonally in a square configuration, so that distance D1equals distance D2 and distance D3 equals distance D4.

The contact press-fit holes 414, like the IDC press-fit holes 416 a-b,are also positioned in a staggered configuration, in order to minimizecrosstalk and corresponding imbalances between adjacent contacts.Further details regarding the contacts and their configuration will beprovided with respect to FIG. 6.

FIG. 5 is an elevation view of a communication plug 200, with the plugbody 202 shown translucent to illustrate internal components. The plug200 includes the plug body 202, circuit board 212, IDCs 302 a-b, andwire guide 210, and is connected to a cable 204 comprising wire pairs208 surrounded by an outer insulative jacket 206. The wire guide 210positions the wire pairs 208 for proper engagement with the IDCs 302a-b.

A feature of the present disclosure is the angled configuration of thecircuit board 212 within the plug body 202. As seen from the side (FIG.5), the circuit board 212 is angled at an angle 502 relative to theincoming cable 204. The angle 502 may also be defined relative to otherobjects in the plug 200, such as a horizontal plane formed by an upperand/or lower surface of the plug body 202, for example. According topreferred embodiments, the angle 502 can be in the range of greater than0 degrees to 20 degrees, in the range of 1 degree to 10 degrees, in therange of 3 degree to 7 degrees, or can be approximately 5 degrees. Otherangles are possible as well, and will depend on the available spacewithin the plug body 202. In general, the angle 502 will be greater than0 degrees, but less than an angle whose tangent is y/x, where y and xrepresent the interior height and length, respectively, of a generallyrectangular interior cross-section of the plug body 202. The upperbounds of the angle 502 will be determined by several factors other thanthe interior geometry of the plug body 202 as well as including thethickness of the circuit board 212, the radius of the insulated wires inthe wire pairs 208, and the geometries of the contacts 304 (see FIGS.3A-3B) and IDCs 302 a-b, according to a preferred embodiment.

Placing the circuit board 212 at an angle creates more room within theplug body 202, particularly the IDC end of the plug body, so that theIDCs 302 a-b can be mounted on both the top and bottom of the circuitboard 212 without interfering with the plug body 202 and withoutrequiring the size of the plug body 202 to be increased. The angle 502also allows the eight metal contacts (in the preferred embodiment) to beshorter than they would otherwise need to be if the circuit board 212were horizontal. This, in turn, minimizes the inherent coupling betweenadjacent contacts and the associated imbalances resulting therefrom.

Placing IDCs 302 a-b on the top and bottom side of the circuit board 212minimizes crosstalk between differential pairs by separating adjacentwire pairs onto opposite sides of the circuit board 212. Another benefitover the typical design shown in FIGS. 1A-1B is that wire pair 3-6 nolonger needs to be split around wire pair 4-5. The required split ofpair 3-6 can instead be achieved in a more controlled manner usingtraces on the circuit board 212. This can result in a much smaller“super-pair” signal being generated in the plug 200, and avoids a majorsource of crosstalk complexity in the wire termination/IDC 302 a-bregion.

FIG. 6 is an isometric view of the circuit board 412 b showing wherecontacts 304 a-b are inserted, according to one embodiment. The circuitboard 412 b could, for example, serve as the circuit board 212 shown inFIGS. 2A-B, 3A-B, and 5. The IDC hole pattern 416 b matches that shownin FIG. 4B.

The circuit board 412 b includes eight staggered holes 414 foraccommodating eight metal contacts 304 a-b. These contacts 304 a-b canbe press fit or soldered to the circuit board 412 b, for example. Thestaggered configuration minimizes crosstalk and the correspondingimbalances between adjacent contacts 304 a-b.

To ensure compliant contact locations to mate with any industry standardRJ45 jack, two different shapes/sizes are provided for the staggeredcontacts 304 a-b, as shown in FIG. 7. A shorter contact 304 a is usedfor the holes 414 that are closer to the edge of the jack end of thecircuit board 416 b, while a longer contact 304 b is used for holes 414that are further from the edge. As illustrated, the pair 3-6 is shownwith longer contacts 304 b, while the other pairs are shown with shortercontacts 304 a. The location and radius of the contacts 304 a-b aredesigned to be compliant with industry standard IEC 60603-7, specifyinga contact radius of 0.020 inch.

FIGS. 8A and 8B are isometric views of an alternative communication plug1200, with the plug body 1202 shown translucent to illustrate internalcomponents. The plug 1200 includes the plug body 1202 connected througha strain relief boot 1214 to a cable 1204 comprising an outer insulatingjacket 1206 located over a plurality of wire pairs 1208.

A wire guide 1210 positions wires from the wire pairs 1208 so that theymay make electrical contact (via IDCs, which are not shown in FIGS. 8Aand 8B) with a circuit board 1212 on a body 1210. The body 1210 ispreferably a molded plastic body upon which the circuit board 1212 islocated. The circuit board 1212 is preferably a flexible printed circuitboard attached to the body 1210. While other implementations may bepossible, the example illustrated in FIGS. 8A-12 is described withrespect to a flexible printed circuit board attached to a molded plasticbody.

The circuit board 1212 is designed to introduce coupling in the datapath (from the wire pairs 1208 to the contacts 1600, see FIG. 12) toprovide an appropriate amount of crosstalk as required by theTIA-568-B.2-10 standard. The circuit board 1212 may include electricalfeatures such as embedded capacitors and inductors arranged to achieve adesired balance and crosstalk performance. The exact values andarrangements of electrical features will depend on the desiredapplication and its accompanying electrical and/or mechanicalconstraints.

FIGS. 9A and 9B are perspective views of an assembly comprising aflexible circuit board 1212, body 1216, and IDCs 1302 for use in thealternative communication plug of FIGS. 8A and 8B. The IDCs 1302 arepreferably press fit into appropriately-sized holes or pockets 1306 inthe back end of the body 1216. Each differential pair from the cable1204 makes contact with the circuit board 1212 through one of the IDCs1302.

The circuit board 1212 (a flexible printed circuit board, in theillustrated example) preferably includes a tin-plated contact pad thatis folded over the rear edges of the body 1216 as shown in FIGS. 9A and9B. Holes may be placed in the circuit board 1212 to correspond to theholes or pockets 1306 in the body 1216. Then, when the IDCs 1302 arepress fit into the holes or pockets 1306, the inherent force creates agas-tight connection between the IDCs 1302 and the circuit board 1212,creating corresponding electrical connections. This configuration alsohelps to secure the circuit board 1212 to the body 1216.

As shown in FIGS. 9A, 9B, and 10A in the illustrated example, the IDCs1302 are located at both ends of the circuit board 1212, toward the topand bottom edges 1308 of the body 1216. This allows the individual wiresin the wire pairs 1208 a-b (not shown in FIGS. 9A and 9B) to berelatively separated when they make contact with the circuit board 1212through the IDCs 1302. This separation of adjacent wires reducescrosstalk between differential pairs 1208 a-b.

Also illustrated in FIG. 10A and/or in FIG. 10B is a plug body 1202,cable 1204, wire guide 1210, and a jack contact assembly 1050 from atypical RJ45 communication jack. The wire guide 1210 is used to positionthe wires in the wire pairs 1208 a-b for proper and repeatableengagement with the IDCs 1302. For example, the wire guide 1210 couldinclude a plurality of slots and/or retention members configured to holdindividual wires in positions corresponding to the location of the IDCs1302.

FIGS. 11A and 11B are perspective views of the assembly of FIG. 9A,showing the IDCs 1302 installed in two alternative configurations. InFIG. 11A, the upper IDCs 1302 a and lower IDCs 1302 b are installed inrespective linear rows aligned at each end of the circuit board 1212 onthe body 1216. In FIG. 11B, the upper IDCs 1302 c are installed at oneend of the circuit board 1212 in a location corresponding to therear-facing upper corners of the body 1216. The lower IDCs 1302 d areinstalled at the other end of the circuit board 1212 in a locationcorresponding to the rear-facing lower corners of the body 1216.

The design shown in FIGS. 8A through 11B does not require that wire pair3-6 be split around wire pair 4-5, as is the case in the typical plugshown in FIGS. 1A and 1B. The split can instead be implemented on thecircuit board 1212 in a more controlled manner, which can result in asmaller “super-pair” signal being generated in the plug. This avoids amajor source of crosstalk complexity in the wire termination/IDC 1302region.

FIG. 12 is a perspective view of the underside of an assembly similar tothe one shown in FIG. 11B, illustrating contact pads 1600 for makingelectrical contact with an industry standard RJ45 jack. The contacts1600 are preferably eight metal contact pads located on the circuitboard 1212 at the end of the body 1216 opposite the IDCs 1302. In theillustrated example, the IDCs 1302 are located at either end of thecircuit board 1212, while the contact pads are located at or around themiddle of the length of the circuit board 1212. The contact pads 1600preferably are configured to present an edge radius that complies withindustry standard IEC 60603-7 (0.020 inch).

The contact pads 1600 can be created by exposing copper on the circuitboard 1212 and plating the copper with nickel and gold after the circuitboard 1212 has been wrapped around (in the case of a flexible circuitboard) and attached to the body 1216. The shape of the body 1216 helpsto ensure that the contacts will have the compliant industry standarddimensions. Since the eight contact pads 1600 are preferably createdfrom traces on the circuit board 1212, they are inherently thin(heightwise), provide relatively small amount of capacitive andinductive coupling between pair conductors, and consequently introducevery little coupling between neighboring contact pads 1600. This canimprove balance performance for the plug.

FIGS. 13-15B illustrate an additional feature that may be included inthe above described embodiments. In order to help attenuate any commonmode signal that may propagate on a particular wire pair in the plug, achoke, such as a surface mount choke, may be included on the circuitboard. Preferably, one choke is included for each of the wire pairs. Byincorporating common mode chokes into the plug design, some Category 6Achannels may be able to tolerate considerably higher levels ofelectromagnetic interference. The common mode chokes will attenuate thecommon mode signals caused by an interfering source, resulting in alower noise level in the channel.

FIGS. 13 and 14 illustrate the choke feature as implemented in theembodiments of FIGS. 2A-7. FIG. 13 shows the plug (having a plug body202, wire guide 210, and strain relief boot 214 connected to a cable204) interfacing with a jack contact assembly 1050, while FIG. 14 showssome of the internal components (e.g. circuit board 212) of the plug,connected to a cable 204 having wire pairs 208. The circuit board 212has two common mode chokes 1802 a on a top side and two common modechokes 1802 b on a bottom side. Thus, there are four total chokes toattenuate common mode signals on each of the four wire pairs 208.

FIGS. 15A and 15B illustrate the choke feature as implemented in theembodiments of FIGS. 8A-12, where the circuit board 1212 is a flexibleprinted circuit board wrapped around the molded body 1216 between twosets of IDCs 1302 a-b. The common mode chokes 1802 c-d are attached tothe bottom side of the circuit board 1212. When the circuit board 1212is wrapped around the body 1216, the chokes 1802 c-d will be positionedwithin pockets 1218 in the body 1216. This allows the size of the body1216 to be large, while still maintaining the overall plug dimensions.

FIG. 16 is a layout of two layers of the PCB used in the plug of FIGS.2A and 2B; FIG. 17 is a layout of the other two layers of the PCB usedin the plug of FIGS. 2A and 2B; and FIG. 17 is a PCB layout of all fourlayers from FIGS. 16 and 17. FIGS. 16-18 illustrate an embodiment forthe locations of the added crosstalk elements (C′″15, C′″16, C′″83, andC′″84), and the common mode chokes. The crosstalk elements are padcapacitors with one side of the capacitor on one layer of the PCB, andthe other side of the capacitor on another layer of the PCB. The commonmode chokes designed for differential signaling applications and includea single ferrite core with each of the two differential coils/conductorswrapped around the core, with the coils being in series with arespective PCB trace. When a differential signal propagates through thechoke, there is an equal and opposite current flow through thedifferential conductors. This produces a cancelling of magnetic fluxwithin the ferrite core resulting in a low impedance path for thedifferential signal. When a common mode signal propagates through thechoke, the current flow through the conductors is equal and in the samedirection of propagation. This produces a cumulative magnetic fluxwithin the ferrite core resulting in increased impedance seen by commonmode signals.

Given the arrangement of the eight plug contacts and conductors in theprior art plug of FIGS. 1A and 1B, there is an inherent amount ofimbalance in the coupling between differential pairs. In the IPC contactregion, the conductor 2 IPC of differential pair 1-2 is much closer inproximity to the conductor 3 IPC of differential pair 3-6 than theconductor 1 IPC of differential pair 1-2. (which is evident in FIGS. 1Aand 1B) This results in an asymmetric crosstalk relationship betweenpair 1-2 and pair 3-6 leading to mode conversion due to the unequalcapacitive loads on conductor 1 and conductor 2 of differential pair1-2. The capacitive crosstalk between pair 1-2 and pair 3-6 is dominatedby this coupling in the IPC contact region.

By reducing the surface area of the plug contacts as shown in FIGS. 6and 7 relative to the plug contacts of FIGS. 1A and 1B, the capacitivecoupling between contacts is reduced and thereby the inherent asymmetriccrosstalk between pair 1-2 and pair 3-6 is reduced. The overallcrosstalk between pairs in turn is also reduced due to the reduction insurface area. To remain in compliance with the plug's differentialcrosstalk requirements in ANSI/TIA-568-C.2, additional crosstalk isadded to the printed circuit board (PCB) in the form of embeddedcapacitors as shown in FIGS. 16-18. A capacitor introduced betweenconductor 1 of pair 1-2 and conductor 6 of pair 3-6 results in anasymmetric crosstalk relationship between pairs 1-2 and pairs 3-6 on thePCB. This asymmetry in the PCB is mirrored with respect to the asymmetryin the contact region. The mode conversion that is introduced by theimbalance in capacitive coupling in the contact region is offset by themode conversion that is introduced by the imbalance in capacitivecoupling on the PCB. The net capacitive crosstalk between pairs 1-2 andpairs 3-6 in the plug is now balanced and the overall mode conversion isminimized due to the equal capacitive load on conductor 1 and conductor2 of pair 1-2.

The crosstalk in the prior art plug of FIGS. 1A and 1B is a function ofthe distributed electrical parameters of the plug contacts and cablewires connected thereto, including particularly the distributedinductance and capacitance of the these components and the correspondingcapacitive and inductive coupling associated therewith. However, thedominant mode of coupling is primarily capacitive due to the plugcontacts, which can be thought of approximately as plate capacitorshaving capacitance proportional to area of the plates (contacts) andinversely proportional to distance between the capacitor plates(contacts). Crosstalk between pair conductors is then approximatelyproportional to the capacitance between pair conductors. We will let CXYbe the crosstalk (roughly proportional to the capacitance betweencontacts) between conductor X and Y, so for pairs 1-2, 3-6 we have

C23−C13+C16−C26 within de-embedded XTLK range of ANSI/TIA-568-C.2  (req.1)

and

C23>>C13>>C26>>C16  (rel. 1)

because of the relative distance between the conductors of pairs 1-2,3-6. Relationship 1 (rel. 1) is indicative of an asymmetric crosstalk(coupling) as none of C23, C13, C26, and C16 are equal, and any plugmeeting the requirements of ANSI/TIA-568-C.2 must conform to Requirement1 (req. 1). Also, for the purpose of the following discussion, andbecause the coupling between contacts 2 and 3 dominate due to relativeproximity, we will let

C23−C13+C16−C26=C′23.  (eq. 1)

In contrast, the present invention has reduced crosstalk in the plugcontact region due to the reduced contact areas, and also has reducedcrosstalk due to the separation of insulation piercing features of theplug contacts into separate, new IDC elements which are connected to aPCB, and which IDC elements can be organized into a semi-balanced orbalanced orientation as previously described. In the present invention,each of the new plug contacts' crosstalk couplings C″23, C″13, C″16,C″26 are individually less than their counterparts C23, C13, C16, C26,respectively, in the prior art plug. Consequently, when C″23, C″13,C″16, C″26 are substituted into Equation 1 (eq. 1), the left hand sideof the equation is less that C′23, and Requirement 1 is also not met,i.e., C″23−C″13+C″16−C″26 can fall outside the de-embedded XTLK range ofANSI/TIA-568-C.2. C″23, C″13, C″16, C″26 still comprise asymmetriccrosstalk (coupling) as they are not all equal. The reduction in the newplug contacts' crosstalks C″23, C″13, C″16, C″26 provides at least onedesign degree of freedom that is used advantageously in the presentinvention.

The present invention adds in an asymmetric crosstalk element C′″16 inthe PCB such that C″23−C″13+C″16-C″26+C′″16 is within de-embedded XTLKrange of ANSI/TIA-568-C.2. Further, the value of C′″16 is selected suchthat

C″23−C″13+C″16−C″26=C′″23 (effective plug contactcrosstalk)=C′″16.  (eq. 2)

C′″16 is a mirrored crosstalk element because C′″16 is placed betweenopposite contact conductors (1-6) when compared to the contactconductors (2-3) the new effective plug contact crosstalk C′″23 iseffectively between. C′″16 is a second asymmetric coupling element inthat the other inherent plug PCB coupling elements for this paircombination, which are due to the distributed electrical parameters ofthe PCB transmission lines, have a significantly lower value than C′″16.When C′″16 is combined with the inherent asymmetric coupling C′″23, abalanced symmetric coupling exists between the individual contacts ofthis pair combination because of the equality, or approximate equality,of Equation 2. There exists in the present invention a balancedsymmetric coupling between the individual contacts for this paircombination leading to minimized mode conversion due to equal capacitiveloading on each conductor of pair 1-2.

The same technique is applied on the PCB with respect to pair 1-2 andpair 4-5 (see component C′″15), pair 3-6 and pair 7-8 (see componentC′″83), and pair 4-5 and pair 7-8 (see component C′″84). For paircombination 3-6, 4-5, it is a naturally balanced symmetric couplingbecause of the split pair 3-6 around pair 4-5; although coupling can beadded between 3-4, and 5-6, in approximately equal amounts, if the levelof the crosstalk for this pair combination needs to be raised to bewithin the de-embedded range. Pair combination 1-2, 7-8 is not ofconcern because of the separation between these pairs and thecorresponding low levels of crosstalk. The balanced nature of the IDCsprovides at least one design degree of freedom that is usedadvantageously in the present invention in that the DC layout aspreviously described also reduces the inherent asymmetric coupling ofthe plug.

While this invention has been described as having a preferred design,the present invention can be further modified within the spirit andscope of this disclosure. This application is therefore intended tocover any variations, uses, or adaptations of the invention using itsgeneral principles. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this invention pertains and which fallwithin the limits of the appended claims.

We claim:
 1. A communication plug comprising: a housing; a printedcircuit board (PCB) positioned at least partially inside said housing; aplurality of cable contacts; a plurality of connector contacts; and aplurality of traces on said PCB, each of said plurality of tracesconnecting one of said cable contacts with one of said connectorcontacts, each said trace with its respective said cable contact andrespective said connector contact forming a signal line, said signallines forming at least a first differential pair and a seconddifferential pair, said signal lines being arranged such that said firstdifferential pair capacitively couples to said second differential pairto provide crosstalk, said signal lines being further arranged such thatsaid capacitive coupling between said first differential pair and saidsecond differential pair is balanced.
 2. The communication plug of claim1, wherein said first differential pair includes a first signal linewith a first connector contact and a second signal line with a secondconnector contact, wherein said second differential pair includes athird signal line with a third connector contact and a fourth signalline with a fourth connector contact, and wherein said balancedcapacitive coupling between said first differential pair and said seconddifferential pair is provided at least in part by said second connectorcontact capacitively coupling to said third connector contact and afirst capacitive coupling element between said first signal line andsaid fourth signal line.
 3. The communication plug of claim 2, whereineach of said first, second, third, and fourth signal lines includes arespective first, second, third, and fourth via, each of said first,second, third, and fourth vias respectively connecting each of saidfirst, second, third, and fourth connector contacts with one respectivesaid trace, and wherein said balanced capacitive coupling between saidfirst differential pair and said second differential pair is furtherprovided at least in part by said second via capacitively coupling tosaid third via.
 4. The communication plug of claim 2, wherein saidsignal lines further form a third differential pair that includes afifth signal line with a fifth connector contact and a sixth signal linewith a sixth connector contact, and wherein said signal lines arefurther arranged such that said second differential pair capacitivelycouples to said third differential pair to provide crosstalk, saidsignal lines are also further arranged such that said capacitivecoupling between second differential pair and said third differentialpair is balanced.
 5. The communication plug of claim 4, wherein saidbalanced capacitive coupling between said second differential pair andsaid third differential pair is provided at least in part by said fourthconnector contact capacitively coupling to said fifth connector contactand a second capacitive coupling element between said third signal lineand said sixth signal line.
 6. The communication plug of claim 5,wherein at least one of said first capacitive coupling element and saidsecond capacitive coupling element is a capacitor.
 7. The communicationplug of claim 6, wherein said capacitor is a pad capacitor.
 8. Acommunication cable comprising: a plurality of conductors; and acommunication plug including: a housing; a printed circuit board (PCB)positioned at least partially inside said housing; a plurality of cablecontacts, each of said cable contact connected with one of saidconductors; a plurality of connector contacts; and a plurality of traceson said PCB, each of said plurality of traces connecting one of saidcable contacts with one of said connector contacts, each said trace withits respective said cable contact and respective said connector contactforming a signal line, said signal lines forming at least a firstdifferential pair and a second differential pair, said signal linesbeing arranged such that said first differential pair capacitivelycouples to said second differential pair to provide crosstalk, saidsignal lines being further arranged such that said capacitive couplingbetween said first differential pair and said second differential pairis balanced.
 9. The communication cable of claim 8, wherein said firstdifferential pair includes a first signal line with a first connectorcontact and a second signal line with a second connector contact,wherein said second differential pair includes a third signal line witha third connector contact and a fourth signal line with a fourthconnector contact, and wherein said balanced capacitive coupling betweensaid first differential pair and said second differential pair isprovided at least in part by said second connector contact capacitivelycoupling to said third connector contact and a first capacitive couplingelement between said first signal line and said fourth signal line. 10.The communication cable of claim 9, wherein each of said first, second,third, and fourth signal lines includes a respective first, second,third, and fourth via, each of said first, second, third, and fourthvias respectively connecting each of said first, second, third, andfourth connector contacts with one respective said trace, and whereinsaid balanced capacitive coupling between said first differential pairand said second differential pair is further provided at least in partby said second via capacitively coupling to said third via.
 11. Thecommunication cable of claim 9, wherein said signal lines further form athird differential pair that includes a fifth signal line with a fifthconnector contact and a sixth signal line with a sixth connectorcontact, and wherein said signal lines are further arranged such thatsaid second differential pair capacitively couples to said thirddifferential pair to provide crosstalk, said signal lines are alsofurther arranged such that said capacitive coupling between seconddifferential pair and said third differential pair is balanced.
 12. Thecommunication cable of claim 11, wherein said balanced capacitivecoupling between said second differential pair and said thirddifferential pair is provided at least in part by said fourth connectorcontact capacitively coupling to said fifth connector contact and asecond capacitive coupling element between said third signal line andsaid sixth signal line.
 13. The communication cable of claim 12, whereinat least one of said first capacitive coupling element and said secondcapacitive coupling element is a capacitor.
 14. The communication cableof claim 13, wherein said capacitor is a pad capacitor.
 15. Acommunication plug comprising: a housing; a printed circuit board (PCB)positioned at least partially inside said housing; a plurality of cablecontacts; a plurality of connector contacts; and a plurality of traceson said PCB, each of said plurality of traces connecting one of saidcable contacts with one of said connector contacts, each said trace withits respective said cable contact and respective said connector contactforming a signal line, said signal lines forming at least a firstdifferential pair and a second differential pair, said signal linesbeing arranged such that said first differential pair couples to saidsecond differential pair to provide crosstalk, said signal lines beingfurther arranged such that said coupling between said first differentialpair and said second differential pair is balanced.
 16. Thecommunication plug of claim 1, wherein said first differential pairincludes a first signal line with a first connector contact and a secondsignal line with a second connector contact, wherein said seconddifferential pair includes a third signal line with a third connectorcontact and a fourth signal line with a fourth connector contact, andwherein said balanced coupling between said first differential pair andsaid second differential pair is provided at least in part by saidsecond connector contact coupling to said third connector contact and afirst coupling element between said first signal line and said fourthsignal line.
 17. The communication plug of claim 2, wherein each of saidfirst, second, third, and fourth signal lines includes a respectivefirst, second, third, and fourth via, each of said first, second, third,and fourth vias respectively connecting each of said first, second,third, and fourth connector contacts with one respective said trace, andwherein said balanced coupling between said first differential pair andsaid second differential pair is further provided at least in part bysaid second via coupling to said third via.
 18. The communication plugof claim 2, wherein said signal lines further form a third differentialpair that includes a fifth signal line with a fifth connector contactand a sixth signal line with a sixth connector contact, and wherein saidsignal lines are further arranged such that said second differentialpair couples to said third differential pair to provide crosstalk, saidsignal lines are also further arranged such that said coupling betweensecond differential pair and said third differential pair is balanced.19. The communication plug of claim 4, wherein said balanced couplingbetween said second differential pair and said third differential pairis provided at least in part by said fourth connector contact couplingto said fifth connector contact and a second coupling element betweensaid third signal line and said sixth signal line.
 20. The communicationplug of claim 5, wherein at least one of said first coupling element andsaid second coupling element is a capacitor.